Alternator belts only lasting 2 months

[BMW BMXER]

My car is shredding the inside (farthest from the fan) part of my alternator belts. I had the fan pump pulley replaced (cost way too much) and its still doing it. Alternator pulley perhaps?

The alternators from a 91 325is and it appears to be bushingless. I got it for 50 dollars and rebuilding my old one is $150 should I just swap the pulleys?

Any other ideas?

[325 eta]

its the pulley check for dents .? is it a new pulley????

[BMW BMXER]

The alternator no.

The water pump yes

[bmwguru007]

Something is wrong with the alignment of the pulleys or a pulley itself. Watch while the car is running to see if the belt is wobbling or running at an angle relative to the other belts. Otherwise, like 325 eta said, a pulley may be damaged causing the abnormal wear. Check the pulleys for any defects. This includes the crank pulley. If you recently had work done that required it to be removed ( timing belt, water pump) it could have gotten damaged while it was off. I just came up with another idea after I wrote all of the above. For the record, what year and model is your car? Two brands of alternators (Bosch and Valeo) were installed on e30s. They are interchangable, but they each use a unique pulley and fan wheel. This simply means you cannot use a pulley or fan wheel from a Valeo on a Bosch or vise versa. So if for some reason the wrong pulley and/or fan wheel was installed I'm guessing it could cause the kind of problem you are having.

[DaN]

For the record, what year and model is your car? Two brands of alternators (Bosch and Valeo) were installed on e30s. They are interchangable, but they each use a unique pulley and fan wheel. This simply means you cannot use a pulley or fan wheel from a Valeo on a Bosch or vise versa. So if for some reason the wrong pulley and/or fan wheel was installed I'm guessing it could cause the kind of problem you are having.

I have an 85 325e
I think I am having that problem, I replaced my alternator which was a Bosch, with one thats not a bosch. The pulley on the alternator seems to be too wide, the belt sits real low in the groove. It's also adjusted all the way out, but its not enough to get the belt tight, so it runs pretty loose. I haven't had any problems with squeeling or charging so it hasn't gotten fixed yet.

Will the bosch pulley fit on the other style alternator?
Where can I get the pulley?
Thanks

[bmwguru007]

Dan you didn't say if your alternator was a Valeo, you just said it wasn't a Bosch. I have both pulleys sitting in front of me and the Bosch one is wider and deeper than the Valeo one. This makes me think you have a Bosch pulley. To answer your question, either brand pulley will fit on either brand alternator. So, if you have a Valeo alternator then you could have the wrong (Bosch) pulley on it. I'm not exactly sure what if any problems that would cause. I'm guessing your problem is due to your belt being stretched. I highly doubt the pulley could prevent you from being able to tension the belt. The difference in diameter between the Bosch and Valeo pulleys is negligible considering the range of the alternator's adjuster mechanism. Either way, if you get a chance check it out. You can get the pulley for sure from the dealer, used from someone or a junkyard, or possibly online.

[BMW BMXER]

I have an 1985 eta with a 1991 325is Alternator.

So I am a tad confused. Can I swap the pulleys or not?

Also people keep telling me about alternator bushings. I can located them fine on the old one but as I said the new one appears to be solid. I belive my old alternator (which I still have) is a bosch but I am unsure about the new one. I know that they are infact different just by the busing issue.

[Charlie]

Check the bushings on all your accessories items, alternator, PS pump, AC compressor, et. all. If any of them are worn out, they can deflect under engine load, putting a lot of stress on the belts.

-Charlie

[bmwguru007]

If your old alternator has bushings it is a Bosch. You can only swap the pulleys if the alternator from the 91 325is is a Bosch also! You'll have to check it to see what brand (Bosch or Valeo) it is. The best way to tell while it is on the car is to look at the back side of the alternator. The back of a Bosch model will be metal and have a black external voltage regulator attached to it, while the back of a Valeo will be a black plastic cover. You are correct, the newer cars used alternators with solid mounts, thus eliminating the problem of worn bushings. That isn't the problem, it will work on your car either way. Go have a look at your alternator and see if you can identify it using the above descriptions.